Injection devices of the kind where a dose setting member is operable to set a desired dose by rotation of the dose setting member are known in the art. An example of such an injection device is an elongated device also known as an injection pen, due to its resemblance with a pen.
In order to reduce the pressure needed to be applied by a user to cause a set dose to be expelled from an injection device, it is desirable to provide a gearing arrangement in the injection device in order to allow for an injection button to have a larger stroke than a piston.
US 2004/0059299 discloses an injection device having such a gearing arrangement in the form of a gear box. The gear box is fixed in a housing of the injection device in a way that allows the gear box to rotate in the housing but not to be axially displaced relative to the housing. Thus, during dose setting, the gear box rotates along with the dose knob. In order to allow this rotation of the gear box, a relatively large space needs to be accommodated inside the housing, even though the gear box will only occupy a relatively small part of the accommodated space at any given time. Thereby the injection device becomes relatively bulky.